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Tester or
Instrumentation Circuits, Page 3d
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Last Updated on:
Wednesday, November 29, 2017 05:38 AM |
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Circuits Designed by Dave Johnson, P.E. : |
- CAPACITANCE
TYPE LIQUID LEVEL MONITOR
This circuit was originally designed to monitor the level of liquid natural gas in a
tank but it can be used to also measure almost any liquid. Two custom insulated
metal tubes form a capacitor plate. The capacitance between the two tubes increases
as the level of the liquid rises. The circuit converts an increase of capacitance
into a positive voltage change. The circuit could be changed to handle almost any
scale factor needed.
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- Cheap
Electrostatic Discharge Tester
Anyone who has ever had a shocking experience on an
especially dry day is acutely aware of the kinds of high voltage that can be
generated from a simple walk across a carpeted floor. Those same finger to metal
sparks can destroy or disrupt sensitive electronic circuits. Good design practices
take great care to avoid such potential disasters by maintaining sufficient
insulation between metal or plastic enclosure parts and the electronics within or by
shielding any especially sensitive components....
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- Cheap Light
Power Meter
Some time ago I was experimenting with the use of some low leakage photovoltaic
solar cells, to harvest some energy from the diffuse lighting inside a room.
The plan was to use a small array of solar cells (the type often used on solar
powered calculators) to keep a super capacitor charged, drawing power from the light
within an inside room...
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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Clear Fluid Detector-2 - Using an ultra low power technique, this
circuit detects when a clear fluid is inside a piece of clear plastic
tubing. It can be used for fluid level control and monitoring. …. [Designed
by David A. Johnson] |
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Clear Fluid Detector-3 - This circuit detects when a clear fluid
is inside a piece of clear plastic tubing. It can be used for fluid level
control and monitoring. …. [Designed by David A. Johnson] |
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Clear Fluid Monitor - An optical technique seemed like the best
choice for this application. The simple circuit below works well but
only when the light detector can be shielded from bright ambient light.
A visible red LED launches light pulses through the side of the clear tubing
and emerges at the opposite side. A phototransistor forms a light
detector. The circuit takes advantage of the lens effect from any
clear fluid inside the tubing. When there is only air in the tubing,
the light scatters and spreads out quickly before it reaches the
phototransistor.... [Designed by David A. Johnson] |
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Closed-Caption Decoder - This is a closed-caption decoder with
serial output based on a Microchip PIC16F628A. The internal comparators of
the PIC16F628A are used to implement a peak detector and data slicer....
[The hardware was designed by Richard Ottosen, and the firmware was written
by Eric Smith] |
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Cloud Charge Monitor - The Cloud Charge Monitor is an extremely sensitive
device capable of detecting subtle (and not-sosubtle) changes in the accumulated
charge overhead. The device consists of a charge-sensing antenna, a 60 Hz notch
filter, a self-zeroing integrator, a signal limiter, and a leakage zero
adjustment....(circuit / schematic design added 04/05/06) |
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CMOS IC audio oscillator - This circuit consists of a CMOS square wave
oscillator on a frequency of approximately 1 kHz. The RC filter, which has a
roll-off frequency of 500 Hz, filters the harmonics, providing a sine-wave output.
The oscillator has many uses – sidetone circuits in transmitters and signal injectors
for audio tests are just two.... [from Peter Parker's website] |
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CMOS Logic Probe - This circuit uses the four 2 input NOR gates contained
within the 4001 CMOS IC, and is primarily intended for testing cmos circuits. The
probe derives its power from the supply of the circuit being tested. The first gate,
N1, has its inputs tied together so that it operates as an inverter, and it is biased
by R1 so that roughly half the supply potential appears at its output.…. [Tony van
Roon's circuit] |
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CN-7: Testing of COP400 Family Devices - National Semiconductor Application
Note (app note added 2/06) |
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Coax connectors make Low cost test pieces - 06/22/00 EDN-Design Ideas....
EDN is migrating links. This link is not verified. Search the "title" + "EDN"
for new link. |
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Coil Coupled Operation Metal Detector - A Coil Coupled Operation Metal
Detector made from readily obtainable components and using an ordinary medium receiver
as a detector…. [Copyright Rev. Thomas Scarborough] |
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Colour Sensor - Colour sensor is an interesting project for hobbyists. The
circuit can sense eight colours, i.e. blue, green and red (primary colours); magenta,
yellow and cyan (secondary colours); and black and white. The circuit is based on the
fundamentals of optics and digital electronics. The object whose colour is required to
be detected should be placed in front of the system. The light rays reflected from the
object will fall on the three convex lenses which are fixed in front of the three LDRs.
The convex lenses are used to converge light rays. This helps to increase the
sensitivity of.... |
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